Process of purifying dextrose sugar solutions



.Patented Jan. 7,1947

PROCESS OF PUBIFYING DEXTBOSE SUGAR SOLUTIONS Abraham Sidney Behrlnan, Chicago, Hildlng B.

Gnatafson, Bimdale, and James C. Healer, Chim 111., assignors to Infilco Incorporated, Chieago, 111., a corporation of Delaware No Drawing.

This invention relates to the purification of aqueous solutions and has reference more particularly to a process of refining or purifying dextrose solutions containing contaminating metallic ions such as iron and copper.

In the acid conversion of starch products, a slurry of starch is subjected to the action of hydrochloric acid or other, inorganic acids to convert the starch to dextrose. In the starch conversion process, there are produced a relatively large number of complex organic bodies which are not dextrose and a conversion liquor is highly acid by reason of the residual or remaining conversion acid not taken up by the hydrolysis reaction. I a

In the pending application of Henry A. Vallez entitled Process for refining and purifying of sugar ju ces. Serial No. 396.083. filed May 31. 1941, now Patent No. 2,388 194. the proposal iS made that sucrose sugar juces be purified by carbon and regenerate first subecting the rawsugar juice toa limin and carbonation process whereby the pH of the juice is brought to approximately 7 or near neutrality. The still relatively impure sugar juice -is then passed through va bed of hydrogen exchange material such as hydrogen carbonaceous zeolite, then through a bed of activated carbon to remove certain colloidalmatter and colored bodies, and then through a bed of acid adsorption resin to remove the free acid in the juice which is liberated when the bases or metals are through a bed of acid adsorbing resin. It has beenfound, however, that the non-sugar organic Application August 14, 1942, Serial No. 454,874

5 Claims. ,(Cl. 127-46) 2 said beds for future use. The active carbon bed may be rinsed with water after regeneration to remove excess alkali and then a small quantity of acid such as sulfuric or hydrochloric acid may be passed through the active carbon bed to remove the last'traces of alkali.

We have .found that the converter liquid not only contains organic impurities wh ch are nonsugar in character, but also contains iron and copper, and these metallic ions have a tendency to accumulate in the bed of acid adsor tion resin and eventually interfere seriously with the regeneration of said acid adsorbing bed by the means of the'alkaline solution. In view of the fact that this converter liquid is highly acid and contains approx mately 1500 P. P. M. of free acid there was considerable doubt whether these metal ions could be removed prior to the treatment of the converter liquid with the active carbon, by

zeolite is subsequently regenerated with a still stronger acid than that present in the converter liquid.

In order to exemplify the process. we passed approximately 500 ml. of converter liquid through a 50 ml. bed of hydrogen carbonaceous zeolite impurities of the converter liquid should be previously removed by passing the converter liquid through a bed of active carbon to remove the organic impurities of a non-sugar character which would otherwise interfere with the regeneration of the resin acid adsorbing bed. After the acid adsorbing bed is exhausted, it is regenerated by first rinsing out the acid adsorbing bed with water and then passing .a dilute solution of sodium hydroxide or other alkali first through the acid adsorbing bed and then through the bed of active carbon to remove impuritiesfrom both the acid adsorbing bed andrthe active I' ilueut which had previously been regenerated with 300 ml. of half normal hydrochloric acid and washed. The rate offlow was equivalent to one gallon per square foot area per minute. Samples of the eiliuent were analyzed and compared wizh the influent content of copper and iron. The results obtained are indicated below:

P. P. M.

Efiluent When the removal of copper and iron from the converter liquid was found to be feasible, a numconverter liquid. The following table indicates the results obtained in this experimental run us- 3 ing a synthetic solution of iron, copper and acid, but containing no dextrose, but containing the amount of copper, iron and acid found in the converter liquid.

and produced only slightly lower efliciencies in removal of iron and copper ions by the hydrogen carbonaceous zeolite. The sulfuric acid is slightly to be preferred for regeneration since hydrochloric acid is extremely corrosive to iron and Influent characteristics steel- It is obvious from the preceding description Acidity M31 H31 that our improved procerswill operate satisfaccu 175 R R M torily whether or not the solution being treated Fe 130 P P M I contains dextrose and organic impurities. The process may be applied to acid water in general. The term a substantial quantity of free acid Fe cu or a strongly acid solution," which is used to No Volume, designate the type or solution being treated, in-

" Mgm Man dicates a solution of the type specified in the example, namely, one of about .03 normal, which 1 (H 0 2 M My M is the equivalent of a solution with a pH of about 2 1.02.0 .2 .2 .5 .5 1.5. The term materially stronger, used in 2 @318; ;g f :2 connection with the strength of the regenerating 5 4.0-5.0. .3 .3 -6 acid, is used to designate the relative strength Q8198: :3 g, of regenerating acid solution. It is believed oh- 8 7.0-1.25 2.8 -.7 4-6 1-12 vious, as shown in the example, that the strength I g of the regenerating solution may be of the order 4 3 z mmof a .-5 normal solution.

Emuent Aliquot: 7.25 1. Regeneration: 300 ml. N/2 H01 Q Fe Cu Fe Cu Catlonsrecovered.--

:?,$ C s recovered 1% We would state in conclusion that while the ex- Fe Cu. amples illustrated constitute practical embodiments of our invention, we do not wish to limit Cations introduced, mgm 93.0 12 -0 ourselves precisely to these details, since manig gfilg gg ggg 8:}, 8:8 festly, the same may be considerably varied Per cent removal cations 1 6 40 without departing from the spirit of the invention as defined in the appended claims. 1 Determinedimm, MW Having thus described our invention, we claim as new and desire to secure by Letters Patent:

It will be noted that an efiiciency of 94 /2% was In the method of purifying strongly acldic obtained in the removal of the iron ion and an efconvert liquor contaiPmg dextrose and ficiency of 93% in the removal of copper ion, sugardmpurities includmg trace of and which results were highly gratifying in View of copper, organic impurities andasubstantialquanthe fact that the converter liquid is so strongly my 0f free acid, by treatment wlth an 931d m sorbing resin, the step of first removing sub- In order to make certain that the hydrogen s ntialiy all of said iron and copper by passing zeolite would continue to remove the copper and said solution through a bed of hydrogen exiron ions with unimpaired efliciency .over a long change material prior to said treatment of said period of time, a sample of hydrogen carbonasolution with the acid-adsorbing resin. ceous zeolite was employed in an automatically 2. The method of removing substantially all of operated device wherein the zeolite was exhaustt 1 d copper from dextrose convertor ed and regenerated without interruption for a liquor of a pH of the order of about 1.5 and conlarge number of cycles. The material was subm g traces of iron and copper which jected to 50 cycles of continuous regeneration prises passing said liquor through a body of and exhaustion. Each cycle consisted of regencation exchange material operating on the eration with 300 ml. of N/2 hydrochloric acid and dmgen cycle exhaustion at gaufm per square ,foot per 3. The method of treating convertor liquor of a i i rate on synthetl'? wager solution pH of the order of about 1.5 and containing traces g g f 'gg i gg f g gfiz i gg z f g g j of iron and copper to remove substantially all of A sample of the emuent ,water at different points fif g is 3: 2???Z$Zt$i2if of the bed exhaustion gave values of copper and mg S q r I g th iron which agree closely with the results of the nal operanpg on'the hydrogen W 6 manual tests heretofore described in detail. At after'trea'tmg the s puflfied hquor with an the termination of 50 cycles of 4 hours each, the gggggiziz g matenal operating on the material was again tested manually and it was found that there was no falling oif in capacity The method of removing substantially an at the end of the 50 cycles. Tests were also made of the mm and copper from a strongly 3 using sulfuric acid for regeneration of the hydro- Vertor liquor fionta-ining traces of iron a P- gen carbonaceous zeolite and it was found that Per, which Co pr se treating Said convertor the sulfuric acid could be used as a regenerant liquor with a hydrogen exchange material.

iron and copper by passing said liquor through a bed or hydrogen carbonaceous exchange material which has previously been regenerated with an acid solution materially stronger than the acidity of said convertor liquor, and then removing substantially all of the acidity therefrom by passing said converter liquor through a bed of anion exchange material.

ABRAHAM SIDNEY HILDING B. GUSTAFSON. JAMES C. HESLER. 

